Abstract : The United States is at grave risk of a future pyro-terrorist attack. We must define the threat, understand America's vulnerabilities with regard to it, and take action to mitigate this danger to our homeland. While America focuses on the readily apparent scenarios of smuggled nuclear weapons and radiological bombs, Al Qaeda and other terrorist organizations are adapting to avoid our security and screening systems. Instead of using expensive, complex, and readily detectable nuclear or radiological bombs, a future terrorist could easily ignite multiple massive wildfires that would severely damage our regional economies, impact our military forces, and terrorize the American population. An opportunistic terrorist could create a conflagration potentially equal to a multi-megaton nuclear weapon. This phenomenon is defined as pyro-terrorism: the use of arson attacks to terrorize the civilian population and coerce the government to comply with the terrorists' political or social objectives. Arson, the destruction of property with fire for profit or revenge, is the tactic. It is the political and psychological intent that differentiates pyro-terrorism from arson. This paper will describe pyro-terrorism, discuss how existing terrorism tactics and future intent define the threat, assess America's vulnerability to pyro-terrorism, and identify various actions the U.S. Government must take to mitigate this vulnerability. If terrorist organizations use arson as a tactic, and publicly assume responsibility for the massive fires it causes, the perception of a secure homeland among the populace would quickly erode. The fire's devastation could overwhelm suppression resources, weaken regional economies, destroy critical infrastructure, effect readiness in military forces, and put political pressure on national leadership for policy change.